diff --git a/client/src/components/App.tsx b/client/src/components/App.tsx
index f0b3e67..adfb1ae 100644
--- a/client/src/components/App.tsx
+++ b/client/src/components/App.tsx
@@ -1,4 +1,4 @@
-import React, { FunctionComponent, useState } from 'react';
+import React, { FunctionComponent, useState, useEffect } from 'react';
 import { BrowserRouter, Route, Redirect, Switch } from "react-router-dom";
 import { HomePage } from './HomePage/HomePage';
 import { ProfilePage } from './ProfilePage/ProfilePage';
@@ -6,44 +6,76 @@ import { WorkgroupPage } from './WorkgroupPage/WorkgroupPage';
 import { DecisionSupportFilePage } from './DecisionSupportFilePage/DecisionSupportFilePage';
 import { DashboardPage } from './DashboardPage/DashboardPage';
 import { useUserProfile } from '../gql/queries/profile';
-import { LoggedInContext } from '../hooks/useLoggedIn';
+import { LoggedInContext, getSavedLoggedIn, saveLoggedIn } from '../hooks/useLoggedIn';
 import { PrivateRoute } from './PrivateRoute';
 import { useKonamiCode } from '../hooks/useKonamiCode';
 import { Modal } from './Modal';
+import { createClient } from '../util/apollo';
+import { ApolloProvider } from '@apollo/client';
+import { LogoutPage } from './LogoutPage';
 
 export interface AppProps {
 
 }
 
+
+
 export const App: FunctionComponent<AppProps> = () => {
-  const { user } = useUserProfile();
+  const [ loggedIn, setLoggedIn ] = useState(getSavedLoggedIn());
+
+  const client = createClient((loggedIn) => {
+    setLoggedIn(loggedIn);
+  });
+
+  useEffect(() => {
+    saveLoggedIn(loggedIn);
+  }, [loggedIn]);
 
   const [ showBoneyM, setShowBoneyM ] = useState(false);
   useKonamiCode(() => setShowBoneyM(true));
 
   return (
-    <LoggedInContext.Provider value={user.id !== ''}>
-      <BrowserRouter>
-        <Switch>
-          <Route path="/" exact component={HomePage} />
-          <PrivateRoute path="/profile" exact component={ProfilePage} />
-          <PrivateRoute path="/workgroups/:id" exact component={WorkgroupPage} />
-          <PrivateRoute path="/decisions/:id" exact component={DecisionSupportFilePage} />
-          <PrivateRoute path="/dashboard" exact component={DashboardPage} />
-          <Route component={() => <Redirect to="/" />} />
-        </Switch>
-      </BrowserRouter>
-      {
-        showBoneyM ?
-        <Modal active={true} showCloseButton={true} onClose={() => setShowBoneyM(false)}>
-          <iframe width={560} height={315}
-            frameBorder={0}
-            allowFullScreen={true}
-            src="https://www.youtube.com/embed/uVzT5QEEQ2c?autoplay=1" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture">
-          </iframe>
-        </Modal> :
-        null
-      }
-    </LoggedInContext.Provider>
+    <ApolloProvider client={client}>
+      <LoggedInContext.Provider value={loggedIn}>
+        <UserSessionCheck setLoggedIn={setLoggedIn} />
+        <BrowserRouter>
+          <Switch>
+            <Route path="/" exact component={HomePage} />
+            <PrivateRoute path="/profile" exact component={ProfilePage} />
+            <PrivateRoute path="/workgroups/:id" exact component={WorkgroupPage} />
+            <PrivateRoute path="/decisions/:id" exact component={DecisionSupportFilePage} />
+            <PrivateRoute path="/dashboard" exact component={DashboardPage} />
+            <PrivateRoute path="/logout" exact component={LogoutPage} />
+            <Route component={() => <Redirect to="/" />} />
+          </Switch>
+        </BrowserRouter>
+        {
+          showBoneyM ?
+          <Modal active={true} showCloseButton={true} onClose={() => setShowBoneyM(false)}>
+            <iframe width={560} height={315}
+              frameBorder={0}
+              allowFullScreen={true}
+              src="https://www.youtube.com/embed/uVzT5QEEQ2c?autoplay=1" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture">
+            </iframe>
+          </Modal> :
+          null
+        }
+      </LoggedInContext.Provider>
+    </ApolloProvider>
   );
-}
\ No newline at end of file
+}
+
+interface UserSessionCheckProps {
+  setLoggedIn: (boolean) => void
+}
+
+const UserSessionCheck: FunctionComponent<UserSessionCheckProps> = ({ setLoggedIn }) => {
+  const { user, loading } = useUserProfile();
+
+  useEffect(() => {
+    if (loading) return;
+    setLoggedIn(user.id !== '');
+  }, [user]);
+
+  return null;
+};
\ No newline at end of file
diff --git a/client/src/components/DashboardPage/DecisionSupportFilePanel.tsx b/client/src/components/DashboardPage/DecisionSupportFilePanel.tsx
index 1fa31e8..ba8929d 100644
--- a/client/src/components/DashboardPage/DecisionSupportFilePanel.tsx
+++ b/client/src/components/DashboardPage/DecisionSupportFilePanel.tsx
@@ -26,8 +26,7 @@ export function DecisionSupportFilePanel() {
       itemFilter: (item: Item) => (item as DecisionSupportFile).status === DecisionSupportFileStatus.Closed
     },
   ];
-
-
+  
   return (
     <ItemPanel
       className='is-link'
diff --git a/client/src/components/DashboardPage/ItemPanel.tsx b/client/src/components/DashboardPage/ItemPanel.tsx
index 4335c68..d84860d 100644
--- a/client/src/components/DashboardPage/ItemPanel.tsx
+++ b/client/src/components/DashboardPage/ItemPanel.tsx
@@ -11,8 +11,6 @@ export interface TabDefinition {
   label: string
   itemFilter?: (item: Item) => boolean
 }
-
-
 export interface ItemPanelProps {
   className?: string
   itemIconClassName?: string
@@ -30,9 +28,12 @@ export const ItemPanel: FunctionComponent<ItemPanelProps> = (props) => {
   const { 
     title, className, newItemUrl, 
     itemKey, itemLabel, 
-    itemIconClassName, itemUrl
+    itemIconClassName, itemUrl,
   } = props;
   
+  const items = props.items || [];
+  const tabs = props.tabs || [];
+
   const [ state, setState ] = useState({ selectedTab: 0, filteredItems: [] });
 
   const filterItemsForTab = (tab: TabDefinition, items: Item[]) => {
@@ -42,7 +43,6 @@ export const ItemPanel: FunctionComponent<ItemPanelProps> = (props) => {
 
   const selectTab = (tabIndex: number) => {
     setState(state => {
-      const { tabs, items } = props;      
       const newTab = Array.isArray(tabs) && tabs.length > 0 ? tabs[tabIndex] : null;
       return { 
         ...state, 
@@ -61,7 +61,7 @@ export const ItemPanel: FunctionComponent<ItemPanelProps> = (props) => {
         filteredItems: filterItemsForTab(newTab, items),
       }
     });
-  }, [props.items, props.tabs]);
+  }, [items, tabs]);
 
   const itemElements = state.filteredItems.map((item: Item, i: number) => {
     return (
@@ -74,8 +74,6 @@ export const ItemPanel: FunctionComponent<ItemPanelProps> = (props) => {
     );
   });
 
-  const tabs = props.tabs || [];
-
   return (
     <nav className={`panel ${className}`}>
       <div className="level is-mobile panel-heading mb-0">
diff --git a/client/src/components/DashboardPage/WorkgroupsPanel.tsx b/client/src/components/DashboardPage/WorkgroupsPanel.tsx
index c7ea0d1..5bb9684 100644
--- a/client/src/components/DashboardPage/WorkgroupsPanel.tsx
+++ b/client/src/components/DashboardPage/WorkgroupsPanel.tsx
@@ -1,10 +1,7 @@
-import React, { useEffect, useState } from 'react';
+import React, {  } from 'react';
 import { Workgroup, inWorkgroup } from '../../types/workgroup';
-import { User } from '../../types/user';
-import { Link } from 'react-router-dom';
-import { useWorkgroupsQuery, useWorkgroups } from '../../gql/queries/workgroups';
-import { useUserProfileQuery, useUserProfile } from '../../gql/queries/profile';
-import { WithLoader } from '../WithLoader';
+import { useWorkgroups } from '../../gql/queries/workgroups';
+import { useUserProfile } from '../../gql/queries/profile';
 import { ItemPanel, Item } from './ItemPanel';
 
 export function WorkgroupsPanel() {
diff --git a/client/src/components/HomePage/HomePage.tsx b/client/src/components/HomePage/HomePage.tsx
index f455d4e..a3af9ff 100644
--- a/client/src/components/HomePage/HomePage.tsx
+++ b/client/src/components/HomePage/HomePage.tsx
@@ -3,14 +3,15 @@ import { Page } from '../Page';
 import { WelcomeContent } from './WelcomeContent';
 import { useUserProfile } from '../../gql/queries/profile';
 import { useHistory } from 'react-router';
+import { useLoggedIn } from '../../hooks/useLoggedIn';
 
 export function HomePage() {
-  const { user } = useUserProfile();
+  const loggedIn = useLoggedIn();
   const history = useHistory();
 
   useEffect(() => {
-    if (user.id !== '') history.push('/dashboard');
-  }, [user.id])
+    if (loggedIn) history.push('/dashboard');
+  }, [loggedIn])
 
   return (
     <Page title="Accueil">
diff --git a/client/src/components/LogoutPage.tsx b/client/src/components/LogoutPage.tsx
new file mode 100644
index 0000000..56cd70a
--- /dev/null
+++ b/client/src/components/LogoutPage.tsx
@@ -0,0 +1,15 @@
+import React, { FunctionComponent, useEffect } from "react";
+import { saveLoggedIn } from "../hooks/useLoggedIn";
+import { Config } from "../config";
+
+export interface LogoutPageProps {
+  
+}
+
+export const LogoutPage: FunctionComponent<LogoutPageProps> = () => {
+  useEffect(() => {
+    saveLoggedIn(false);
+    window.location.replace(Config.logoutURL);
+  }, []);
+  return null;
+};
\ No newline at end of file
diff --git a/client/src/components/Navbar.tsx b/client/src/components/Navbar.tsx
index a5d38fe..036e8e4 100644
--- a/client/src/components/Navbar.tsx
+++ b/client/src/components/Navbar.tsx
@@ -44,11 +44,11 @@ export function Navbar() {
                       </span>
                       <span>Mon profil</span>
                     </Link>
-                    <a className="button is-warning" href={Config.logoutURL}>
+                    <Link className="button is-warning" to="/logout">
                       <span className="icon">
                         <i className="fas fa-sign-out-alt"></i>
                       </span>
-                    </a>
+                    </Link>
                   </Fragment> :
                   <a className="button is-primary" href={Config.loginURL}>
                     <span className="icon">
diff --git a/client/src/components/WorkgroupPage/InfoForm.tsx b/client/src/components/WorkgroupPage/InfoForm.tsx
index cb3a3f8..9921b36 100644
--- a/client/src/components/WorkgroupPage/InfoForm.tsx
+++ b/client/src/components/WorkgroupPage/InfoForm.tsx
@@ -1,12 +1,13 @@
 import React, { useState, ChangeEvent, useEffect } from 'react';
 import { Workgroup } from '../../types/workgroup';
+import { useIsAuthorized } from '../../gql/queries/authorization';
 
 export interface InfoFormProps {
   workgroup: Workgroup
   onChange?: (workgroup: Workgroup) => void
 }
 
-export function InfoForm({ workgroup, onChange }: InfoFormProps) {  
+export function InfoForm({ workgroup, onChange }: InfoFormProps) {
   const [ state, setState ] = useState({
     changed: false,
     workgroup: {
@@ -17,6 +18,15 @@ export function InfoForm({ workgroup, onChange }: InfoFormProps) {
     }
   });
 
+  const { isAuthorized } = useIsAuthorized({
+    variables: {
+      action: 'update',
+      object: {
+        workgroupId: state.workgroup.id,
+      }
+    }
+  }, state.workgroup.id === '' ? true : false);
+
   useEffect(() => {
     setState({
       changed: false,
@@ -60,7 +70,8 @@ export function InfoForm({ workgroup, onChange }: InfoFormProps) {
       <div className="field">
         <label className="label">Nom du groupe</label>
         <div className="control">
-          <input type="text" className="input" value={state.workgroup.name} 
+          <input type="text" className="input" value={state.workgroup.name}
+            disabled={!isAuthorized}
             onChange={onWorkgroupAttrChange.bind(null, "name")} />
         </div>
       </div>
@@ -85,7 +96,7 @@ export function InfoForm({ workgroup, onChange }: InfoFormProps) {
         null
       }
       <div className="buttons is-right">
-        <button disabled={!state.changed} 
+        <button disabled={!state.changed || !isAuthorized}
           className="button is-success" onClick={onSaveClick}>
           <span>Enregistrer</span>
           <span className="icon"><i className="fa fa-save"></i></span>
diff --git a/client/src/components/WorkgroupPage/WorkgroupPage.tsx b/client/src/components/WorkgroupPage/WorkgroupPage.tsx
index a0a114c..218ec69 100644
--- a/client/src/components/WorkgroupPage/WorkgroupPage.tsx
+++ b/client/src/components/WorkgroupPage/WorkgroupPage.tsx
@@ -2,8 +2,8 @@ import React, { useEffect, useState, Fragment } from 'react';
 import { Page } from '../Page';
 import { WithLoader } from '../WithLoader';
 import { useParams } from 'react-router';
-import { useWorkgroupsQuery } from '../../gql/queries/workgroups';
-import { useUserProfileQuery } from '../../gql/queries/profile';
+import { useWorkgroupsQuery, useWorkgroups } from '../../gql/queries/workgroups';
+import { useUserProfileQuery, useUserProfile } from '../../gql/queries/profile';
 import { MembersPanel } from './MembersPanel';
 import { User } from '../../types/user';
 import { InfoPanel } from './InfoPanel';
@@ -12,17 +12,19 @@ import { useJoinWorkgroupMutation, useLeaveWorkgroupMutation, useCloseWorkgroupM
 
 export function WorkgroupPage() {
   const { id } = useParams();
-  const workgroupsQuery = useWorkgroupsQuery({
+  const { workgroups } = useWorkgroups({
     variables:{
       filter: { 
         ids: [id],
       }
     }
   });
-  const userProfileQuery = useUserProfileQuery();
-  const [ joinWorkgroup, joinWorkgroupMutation ] = useJoinWorkgroupMutation();
-  const [ leaveWorkgroup, leaveWorkgroupMutation ] = useLeaveWorkgroupMutation();
-  const [ closeWorkgroup, closeWorkgroupMutation ] = useCloseWorkgroupMutation();
+  const { user } = useUserProfile();
+  
+  const [ joinWorkgroup ] = useJoinWorkgroupMutation();
+  const [ leaveWorkgroup ] = useLeaveWorkgroupMutation();
+  const [ closeWorkgroup ] = useCloseWorkgroupMutation();
+
   const [ state, setState ] = useState({
     userProfileId: '',
     workgroup: {
@@ -35,14 +37,12 @@ export function WorkgroupPage() {
   });
 
   useEffect(() => {
-    if (!workgroupsQuery.data) return;
-    setState(state => ({...state, workgroup:{ ...state.workgroup, ...workgroupsQuery.data.workgroups[0]}}));
-  }, [workgroupsQuery.data]);
+    setState(state => ({...state, workgroup:{ ...state.workgroup, ...workgroups[0]}}));
+  }, [workgroups]);
 
   useEffect(() => {
-    if (!userProfileQuery.data) return;
-    setState(state => ({...state, userProfileId: userProfileQuery.data.userProfile.id }));
-  }, [userProfileQuery.data]);
+    setState(state => ({...state, userProfileId: user.id }));
+  }, [user]);
 
   const onJoinWorkgroupClick = () => {
     joinWorkgroup({
@@ -54,6 +54,18 @@ export function WorkgroupPage() {
 
   const onLeaveWorkgroupClick = () => {
     leaveWorkgroup({
+      update: (cache, result) => {
+        cache.modify({
+          id: cache.identify(result.data.leaveWorkgroup),
+          fields: {
+            members(existingMembers, { readField }) {
+              return existingMembers.filter(
+                user => state.userProfileId !== readField('id', user)
+              );
+            },
+          },
+        });
+      },
       variables: {
         workgroupId: state.workgroup.id,
       }
@@ -121,16 +133,14 @@ export function WorkgroupPage() {
               </div>
             </div>
           </div>
-          <WithLoader loading={[workgroupsQuery.loading, userProfileQuery.loading, joinWorkgroupMutation.loading, leaveWorkgroupMutation.loading]}>
-            <div className="columns">
-              <div className="column">
-                <InfoPanel workgroup={state.workgroup as Workgroup} />
-              </div>
-              <div className="column">
-                <MembersPanel users={state.workgroup.members as User[]} />
-              </div>
+          <div className="columns">
+            <div className="column">
+              <InfoPanel workgroup={state.workgroup as Workgroup} />
             </div>
-          </WithLoader>
+            <div className="column">
+              <MembersPanel users={state.workgroup.members as User[]} />
+            </div>
+          </div>
         </section>
       </div>
     </Page>
diff --git a/client/src/gql/client.tsx b/client/src/gql/client.tsx
deleted file mode 100644
index d773545..0000000
--- a/client/src/gql/client.tsx
+++ /dev/null
@@ -1,56 +0,0 @@
-import { ApolloClient, InMemoryCache, HttpLink } from '@apollo/client';
-import { Config } from '../config';
-import { WebSocketLink } from "@apollo/client/link/ws";
-import { RetryLink } from "@apollo/client/link/retry";
-import { SubscriptionClient } from "subscriptions-transport-ws";
-import { User } from '../types/user';
-
-const subscriptionClient = new SubscriptionClient(Config.subscriptionEndpoint, {
-  reconnect: true,
-});
-
-const link = new RetryLink({attempts: {max: 2}}).split(
-  (operation) => operation.operationName === 'subscription',
-  new WebSocketLink(subscriptionClient),
-  new HttpLink({ uri: Config.graphQLEndpoint, credentials: 'include' })
-);
-
-const cache = new InMemoryCache({
-  typePolicies: {
-    Workgroup: {
-      fields: {
-        members: {
-          merge: mergeArrayByField<User>("id"),
-        }
-      }
-    }
-  }
-});
-
-export const client = new ApolloClient<any>({
-  cache: cache,
-  link: link,
-});
-
-function mergeArrayByField<T>(fieldName: string) {
-  return (existing: T[] = [], incoming: T[], { readField, mergeObjects }) => {
-    const merged: any[] = existing ? existing.slice(0) : [];
-    const objectFieldToIndex: Record<string, number> = Object.create(null);
-    if (existing) {
-      existing.forEach((obj, index) => {
-        objectFieldToIndex[readField(fieldName, obj)] = index;
-      });
-    }
-    incoming.forEach(obj => {
-      const field = readField(fieldName, obj);
-      const index = objectFieldToIndex[field];
-      if (typeof index === "number") {
-        merged[index] = mergeObjects(merged[index], obj);
-      } else {
-        objectFieldToIndex[name] = merged.length;
-        merged.push(obj);
-      }
-    });
-    return merged;
-  }
-}
\ No newline at end of file
diff --git a/client/src/gql/mutations/dsf.tsx b/client/src/gql/mutations/dsf.tsx
index 4accf85..d37a883 100644
--- a/client/src/gql/mutations/dsf.tsx
+++ b/client/src/gql/mutations/dsf.tsx
@@ -9,7 +9,16 @@ mutation createDecisionSupportFile($changes: DecisionSupportFileChanges!) {
     status,
     sections,
     createdAt,
-    updatedAt
+    updatedAt,
+    workgroup {
+      id,
+      name,
+      members {
+        id,
+        email,
+        name
+      }
+    },
   }
 }`;
 
@@ -27,7 +36,16 @@ mutation updateDecisionSupportFile($id: ID!, $changes: DecisionSupportFileChange
     status,
     sections,
     createdAt,
-    updatedAt
+    updatedAt,
+    workgroup {
+      id,
+      name,
+      members {
+        id,
+        email,
+        name
+      }
+    },
   }
 }`;
 
diff --git a/client/src/gql/mutations/workgroups.tsx b/client/src/gql/mutations/workgroups.tsx
index 417aa19..b950a14 100644
--- a/client/src/gql/mutations/workgroups.tsx
+++ b/client/src/gql/mutations/workgroups.tsx
@@ -1,5 +1,6 @@
-import { gql, useQuery, useMutation } from '@apollo/client';
+import { gql, useQuery, useMutation, FetchResult } from '@apollo/client';
 import { QUERY_WORKGROUP } from '../queries/workgroups';
+import { QUERY_IS_AUTHORIZED } from '../queries/authorization';
 
 export const MUTATION_UPDATE_WORKGROUP = gql`
 mutation updateWorkgroup($workgroupId: ID!, $changes: WorkgroupChanges!) {
@@ -57,7 +58,19 @@ mutation joinWorkgroup($workgroupId: ID!) {
 }`;
 
 export function useJoinWorkgroupMutation() {
-  return useMutation(MUTATION_JOIN_WORKGROUP);
+  return useMutation(MUTATION_JOIN_WORKGROUP, {
+    refetchQueries: ({ data }: FetchResult) => {
+      return [{
+        query: QUERY_IS_AUTHORIZED,
+        variables: {
+          action: 'update',
+          object: {
+            workgroupId: data.joinWorkgroup.id,
+          }
+        }
+      }]
+    }
+  });
 }
 
 const MUTATION_LEAVE_WORKGROUP = gql`
@@ -76,7 +89,27 @@ mutation leaveWorkgroup($workgroupId: ID!) {
 }`;
 
 export function useLeaveWorkgroupMutation() {
-  return useMutation(MUTATION_LEAVE_WORKGROUP);
+  return useMutation(MUTATION_LEAVE_WORKGROUP, {
+    refetchQueries: ({ data }: FetchResult) => {
+      return [{
+        query: QUERY_WORKGROUP,
+        variables: {
+          filter: {
+            ids: [data.leaveWorkgroup.id],
+          }
+        }
+      },
+      {
+        query: QUERY_IS_AUTHORIZED,
+        variables: {
+          action: 'update',
+          object: {
+            workgroupId: data.leaveWorkgroup.id,
+          }
+        }
+      }]
+    }
+  });
 }
 
 const MUTATION_CLOSE_WORKGROUP = gql`
diff --git a/client/src/gql/queries/authorization.tsx b/client/src/gql/queries/authorization.tsx
new file mode 100644
index 0000000..d78a813
--- /dev/null
+++ b/client/src/gql/queries/authorization.tsx
@@ -0,0 +1,19 @@
+import { gql, useQuery } from '@apollo/client';
+import { useGraphQLData } from './helper';
+
+export const QUERY_IS_AUTHORIZED = gql`
+  query isAuthorized($action: String!, $object: AuthorizationObject!) {
+    isAuthorized(action: $action, object: $object)
+  }
+`;
+
+export function useIsAuthorizedQuery(options = {}) {
+  return useQuery(QUERY_IS_AUTHORIZED, options);
+}
+
+export function useIsAuthorized(options = {}, defaultValue = false) {
+  const { data, loading, error } = useGraphQLData<boolean>(
+    QUERY_IS_AUTHORIZED, 'isAuthorized', defaultValue, options
+  );
+  return { isAuthorized: data, loading, error };
+}
\ No newline at end of file
diff --git a/client/src/gql/queries/dsf.tsx b/client/src/gql/queries/dsf.tsx
index e41b5fc..0afbdcb 100644
--- a/client/src/gql/queries/dsf.tsx
+++ b/client/src/gql/queries/dsf.tsx
@@ -16,7 +16,9 @@ export const QUERY_DECISION_SUPPORT_FILES = gql`
         id,
         name,
         members {
-          id
+          id,
+          email,
+          name
         }
       },
     }
diff --git a/client/src/hooks/useLoggedIn.tsx b/client/src/hooks/useLoggedIn.tsx
index 8c92e4d..2764c04 100644
--- a/client/src/hooks/useLoggedIn.tsx
+++ b/client/src/hooks/useLoggedIn.tsx
@@ -1,7 +1,23 @@
-import React, { useState, useContext } from "react";
+import React, { useContext, useEffect } from "react";
 
-export const LoggedInContext = React.createContext(false);
+const LOGGED_IN_KEY = 'loggedIn';
+
+export const LoggedInContext = React.createContext(getSavedLoggedIn());
 
 export const useLoggedIn = () => {
   return useContext(LoggedInContext);
-};
\ No newline at end of file
+};
+
+export function saveLoggedIn(loggedIn: boolean) {
+  console.log("saveLoggedIn", JSON.stringify(loggedIn))
+  window.sessionStorage.setItem(LOGGED_IN_KEY, JSON.stringify(loggedIn));
+}
+
+export function getSavedLoggedIn(): boolean {
+  try {
+    const loggedIn = JSON.parse(window.sessionStorage.getItem(LOGGED_IN_KEY));
+    return !!loggedIn;
+  } catch(err) {
+    return false;
+  }
+}
\ No newline at end of file
diff --git a/client/src/index.tsx b/client/src/index.tsx
index cee36c1..03c2010 100644
--- a/client/src/index.tsx
+++ b/client/src/index.tsx
@@ -2,7 +2,6 @@ import './sass/_all.scss';
 import React from 'react';
 import ReactDOM from 'react-dom';
 import { App } from './components/App';
-import { client } from './gql/client';
 
 import '@fortawesome/fontawesome-free/js/fontawesome'
 import '@fortawesome/fontawesome-free/js/solid'
@@ -12,8 +11,6 @@ import './resources/favicon.png';
 import { ApolloProvider } from '@apollo/client';
 
 ReactDOM.render(
-  <ApolloProvider client={client}>
-    <App />
-  </ApolloProvider>,
+  <App />,
   document.getElementById('app')
 );
diff --git a/client/src/util/apollo.ts b/client/src/util/apollo.ts
new file mode 100644
index 0000000..519dee5
--- /dev/null
+++ b/client/src/util/apollo.ts
@@ -0,0 +1,74 @@
+
+import { ApolloClient, InMemoryCache, HttpLink, from } from '@apollo/client';
+import { Config } from '../config';
+import { WebSocketLink } from "@apollo/client/link/ws";
+import { RetryLink } from "@apollo/client/link/retry";
+import { onError } from "@apollo/client/link/error";
+import { SubscriptionClient } from "subscriptions-transport-ws";
+import { User } from '../types/user';
+
+export function createClient(setLoggedIn: (boolean) => void) {
+  const subscriptionClient = new SubscriptionClient(Config.subscriptionEndpoint, {
+    reconnect: true,
+  });
+  
+  const errorLink = onError(({ operation }) => {
+    const { response } = operation.getContext();
+    if (response.status === 401) setLoggedIn(false);
+  });
+  
+  const retryLink = new RetryLink({attempts: {max: 2}}).split(
+    (operation) => operation.operationName === 'subscription',
+    new WebSocketLink(subscriptionClient),
+    new HttpLink({ 
+      uri: Config.graphQLEndpoint, 
+      credentials: 'include',
+    })
+  );
+  
+  const cache = new InMemoryCache({
+    typePolicies: {
+      Workgroup: {
+        fields: {
+          members: {
+            merge: mergeArrayByField<User>("id"),
+          }
+        }
+      }
+    }
+  });
+  
+  return new ApolloClient<any>({
+    cache: cache,
+    link: from([
+      errorLink,
+      retryLink
+    ]),
+  });
+}
+
+export function mergeArrayByField<T>(fieldName: string) {
+  return (existing: T[] = [], incoming: T[], { readField, mergeObjects }) => {
+    const merged: any[] = existing ? existing.slice(0) : [];
+    
+    const objectFieldToIndex: Record<string, number> = Object.create(null);
+    if (existing) {
+      existing.forEach((obj, index) => {
+        objectFieldToIndex[readField(fieldName, obj)] = index;
+      });
+    }
+
+    incoming.forEach(obj => {
+      const field = readField(fieldName, obj);
+      const index = objectFieldToIndex[field];
+      if (typeof index === "number") {
+        merged[index] = mergeObjects(merged[index], obj);
+      } else {
+        objectFieldToIndex[name] = merged.length;
+        merged.push(obj);
+      }
+    });
+    
+    return merged;
+  }
+}
\ No newline at end of file
diff --git a/cmd/server/container.go b/cmd/server/container.go
index 7b51fd0..d9017f8 100644
--- a/cmd/server/container.go
+++ b/cmd/server/container.go
@@ -5,6 +5,9 @@ import (
 	"net/http"
 	"time"
 
+	"forge.cadoles.com/Cadoles/daddy/internal/model"
+	"forge.cadoles.com/Cadoles/daddy/internal/voter"
+
 	"github.com/wader/gormstore"
 
 	"forge.cadoles.com/Cadoles/daddy/internal/auth"
@@ -99,5 +102,11 @@ func getServiceContainer(ctx context.Context, conf *config.Config) (*service.Con
 
 	ctn.Provide(auth.ServiceName, auth.ServiceProvider(conf.Auth.Rules))
 
+	ctn.Provide(voter.ServiceName, voter.ServiceProvider(
+		voter.StrategyUnanimous,
+		model.NewDecisionSupportFileVoter(),
+		model.NewWorkgroupVoter(),
+	))
+
 	return ctn, nil
 }
diff --git a/internal/config/config.go b/internal/config/config.go
index 9c49eae..3745b4a 100644
--- a/internal/config/config.go
+++ b/internal/config/config.go
@@ -90,7 +90,7 @@ func NewDefault() *Config {
 			Address:                 ":8081",
 			CookieAuthenticationKey: "",
 			CookieEncryptionKey:     "",
-			CookieMaxAge:            int((time.Hour * 1).Seconds()), // 1 hour
+			CookieMaxAge:            int((time.Hour * 24).Seconds()), // 24 hours
 			TemplateDir:             "template",
 			PublicDir:               "public",
 			FrontendURL:             "http://localhost:8080",
diff --git a/internal/graph/authorization_handler.go b/internal/graph/authorization_handler.go
new file mode 100644
index 0000000..e0b936e
--- /dev/null
+++ b/internal/graph/authorization_handler.go
@@ -0,0 +1,59 @@
+package graph
+
+import (
+	"context"
+
+	"forge.cadoles.com/Cadoles/daddy/internal/model"
+	errs "github.com/pkg/errors"
+)
+
+func handleIsAuthorized(ctx context.Context, action string, obj model.AuthorizationObject) (bool, error) {
+	db, err := getDB(ctx)
+	if err != nil {
+		return false, errs.WithStack(err)
+	}
+
+	var object interface{}
+
+	switch {
+	case obj.WorkgroupID != nil:
+		repo := model.NewWorkgroupRepository(db)
+
+		workgroup, err := repo.Find(ctx, *obj.WorkgroupID)
+		if err != nil {
+			return false, errs.WithStack(err)
+		}
+
+		object = workgroup
+
+	case obj.DecisionSupportFileID != nil:
+		repo := model.NewDSFRepository(db)
+
+		dsf, err := repo.Find(ctx, *obj.DecisionSupportFileID)
+		if err != nil {
+			return false, errs.WithStack(err)
+		}
+
+		object = dsf
+
+	case obj.UserID != nil:
+		repo := model.NewUserRepository(db)
+
+		user, err := repo.Find(ctx, *obj.UserID)
+		if err != nil {
+			return false, errs.WithStack(err)
+		}
+
+		object = user
+
+	default:
+		return false, errs.WithStack(ErrInvalidInput)
+	}
+
+	authorized, err := isAuthorized(ctx, object, model.Action(action))
+	if err != nil {
+		return false, errs.WithStack(err)
+	}
+
+	return authorized, nil
+}
diff --git a/internal/graph/dsf_handler.go b/internal/graph/dsf_handler.go
index c4a1ad3..b0fdc78 100644
--- a/internal/graph/dsf_handler.go
+++ b/internal/graph/dsf_handler.go
@@ -12,6 +12,15 @@ import (
 )
 
 func handleCreateDecisionSupportFile(ctx context.Context, changes *model.DecisionSupportFileChanges) (*model.DecisionSupportFile, error) {
+	authorized, err := isAuthorized(ctx, &model.DecisionSupportFile{}, model.ActionCreate)
+	if err != nil {
+		return nil, errs.WithStack(err)
+	}
+
+	if !authorized {
+		return nil, errs.WithStack(ErrForbidden)
+	}
+
 	ctn := container.Must(ctx)
 	db := orm.Must(ctn).DB()
 
@@ -31,7 +40,21 @@ func handleUpdateDecisionSupportFile(ctx context.Context, id string, changes *mo
 
 	repo := model.NewDSFRepository(db)
 
-	dsf, err := repo.Update(ctx, id, changes)
+	dsf, err := repo.Find(ctx, id)
+	if err != nil {
+		return nil, errs.WithStack(err)
+	}
+
+	authorized, err := isAuthorized(ctx, dsf, model.ActionUpdate)
+	if err != nil {
+		return nil, errs.WithStack(err)
+	}
+
+	if !authorized {
+		return nil, errs.WithStack(ErrForbidden)
+	}
+
+	dsf, err = repo.Update(ctx, id, changes)
 	if err != nil {
 		return nil, errs.WithStack(err)
 	}
@@ -45,7 +68,25 @@ func handleDecisionSupportFiles(ctx context.Context, filter *model.DecisionSuppo
 
 	repo := model.NewDSFRepository(db)
 
-	return repo.Search(ctx, filter)
+	found, err := repo.Search(ctx, filter)
+	if err != nil {
+		return nil, errs.WithStack(err)
+	}
+
+	dsfs := make([]*model.DecisionSupportFile, 0)
+
+	for _, d := range found {
+		authorized, err := isAuthorized(ctx, d, model.ActionRead)
+		if err != nil {
+			return nil, errs.WithStack(err)
+		}
+
+		if authorized {
+			dsfs = append(dsfs, d)
+		}
+	}
+
+	return dsfs, nil
 }
 
 func handleSections(ctx context.Context, dsf *model.DecisionSupportFile) (map[string]interface{}, error) {
diff --git a/internal/graph/error.go b/internal/graph/error.go
new file mode 100644
index 0000000..3e627ce
--- /dev/null
+++ b/internal/graph/error.go
@@ -0,0 +1,8 @@
+package graph
+
+import "errors"
+
+var (
+	ErrForbidden    = errors.New("forbidden")
+	ErrInvalidInput = errors.New("invalid input")
+)
diff --git a/internal/graph/helper.go b/internal/graph/helper.go
index 3351cc7..1607490 100644
--- a/internal/graph/helper.go
+++ b/internal/graph/helper.go
@@ -3,6 +3,8 @@ package graph
 import (
 	"context"
 
+	"forge.cadoles.com/Cadoles/daddy/internal/voter"
+
 	"forge.cadoles.com/Cadoles/daddy/internal/model"
 	"forge.cadoles.com/Cadoles/daddy/internal/orm"
 	"forge.cadoles.com/Cadoles/daddy/internal/session"
@@ -46,3 +48,31 @@ func getSessionUser(ctx context.Context) (*model.User, *gorm.DB, error) {
 
 	return user, db, nil
 }
+
+func isAuthorized(ctx context.Context, obj interface{}, action interface{}) (bool, error) {
+	user, _, err := getSessionUser(ctx)
+	if err != nil {
+		return false, errors.WithStack(err)
+	}
+
+	ctn, err := container.From(ctx)
+	if err != nil {
+		return false, errors.WithStack(err)
+	}
+
+	voterSrv, err := voter.From(ctn)
+	if err != nil {
+		return false, errors.WithStack(err)
+	}
+
+	decision, err := voterSrv.Authorized(ctx, user, obj, action)
+	if err != nil {
+		return false, errors.WithStack(err)
+	}
+
+	if decision == voter.Allow {
+		return true, nil
+	}
+
+	return false, nil
+}
diff --git a/internal/graph/query.graphql b/internal/graph/query.graphql
index 3aca3c6..a84579b 100644
--- a/internal/graph/query.graphql
+++ b/internal/graph/query.graphql
@@ -38,8 +38,15 @@ input DecisionSupportFileFilter {
   ids: [ID]
 }
 
+input AuthorizationObject {
+  workgroupId: ID
+  userId: ID
+  decisionSupportFileId: ID
+}
+
 type Query {
   userProfile: User
   workgroups(filter: WorkgroupsFilter): [Workgroup]!
   decisionSupportFiles(filter: DecisionSupportFileFilter): [DecisionSupportFile]!
+  isAuthorized(action: String!, object: AuthorizationObject!): Boolean!
 }
diff --git a/internal/graph/query.resolvers.go b/internal/graph/query.resolvers.go
index 3cbe791..a36d7de 100644
--- a/internal/graph/query.resolvers.go
+++ b/internal/graph/query.resolvers.go
@@ -31,6 +31,10 @@ func (r *queryResolver) DecisionSupportFiles(ctx context.Context, filter *model1
 	return handleDecisionSupportFiles(ctx, filter)
 }
 
+func (r *queryResolver) IsAuthorized(ctx context.Context, action string, object model1.AuthorizationObject) (bool, error) {
+	return handleIsAuthorized(ctx, action, object)
+}
+
 func (r *userResolver) ID(ctx context.Context, obj *model1.User) (string, error) {
 	return strconv.FormatUint(uint64(obj.ID), 10), nil
 }
diff --git a/internal/graph/workgroup_handler.go b/internal/graph/workgroup_handler.go
index 07f89dd..6eab3e4 100644
--- a/internal/graph/workgroup_handler.go
+++ b/internal/graph/workgroup_handler.go
@@ -2,10 +2,10 @@ package graph
 
 import (
 	"context"
-	"strconv"
 
 	"forge.cadoles.com/Cadoles/daddy/internal/model"
 	"github.com/pkg/errors"
+	errs "github.com/pkg/errors"
 )
 
 func handleWorkgroups(ctx context.Context, filter *model.WorkgroupsFilter) ([]*model.Workgroup, error) {
@@ -24,20 +24,28 @@ func handleWorkgroups(ctx context.Context, filter *model.WorkgroupsFilter) ([]*m
 		}
 	}
 
-	workgroups, err := repo.FindWorkgroups(ctx, criteria...)
+	found, err := repo.FindWorkgroups(ctx, criteria...)
 	if err != nil {
 		return nil, errors.WithStack(err)
 	}
 
+	workgroups := make([]*model.Workgroup, 0)
+
+	for _, wg := range found {
+		authorized, err := isAuthorized(ctx, wg, model.ActionRead)
+		if err != nil {
+			return nil, errs.WithStack(err)
+		}
+
+		if authorized {
+			workgroups = append(workgroups, wg)
+		}
+	}
+
 	return workgroups, nil
 }
 
 func handleJoinWorkgroup(ctx context.Context, rawWorkgroupID string) (*model.Workgroup, error) {
-	workgroupID, err := parseWorkgroupID(rawWorkgroupID)
-	if err != nil {
-		return nil, errors.WithStack(err)
-	}
-
 	user, db, err := getSessionUser(ctx)
 	if err != nil {
 		return nil, errors.WithStack(err)
@@ -45,7 +53,21 @@ func handleJoinWorkgroup(ctx context.Context, rawWorkgroupID string) (*model.Wor
 
 	repo := model.NewWorkgroupRepository(db)
 
-	workgroup, err := repo.AddUserToWorkgroup(ctx, user.ID, workgroupID)
+	workgroup, err := repo.Find(ctx, rawWorkgroupID)
+	if err != nil {
+		return nil, errors.WithStack(err)
+	}
+
+	authorized, err := isAuthorized(ctx, workgroup, model.ActionJoin)
+	if err != nil {
+		return nil, errs.WithStack(err)
+	}
+
+	if !authorized {
+		return nil, errs.WithStack(ErrForbidden)
+	}
+
+	workgroup, err = repo.AddUserToWorkgroup(ctx, user.ID, workgroup.ID)
 	if err != nil {
 		return nil, errors.WithStack(err)
 	}
@@ -53,12 +75,7 @@ func handleJoinWorkgroup(ctx context.Context, rawWorkgroupID string) (*model.Wor
 	return workgroup, nil
 }
 
-func handleLeaveWorkgroup(ctx context.Context, rawWorkgroupID string) (*model.Workgroup, error) {
-	workgroupID, err := parseWorkgroupID(rawWorkgroupID)
-	if err != nil {
-		return nil, errors.WithStack(err)
-	}
-
+func handleLeaveWorkgroup(ctx context.Context, workgroupID string) (*model.Workgroup, error) {
 	user, db, err := getSessionUser(ctx)
 	if err != nil {
 		return nil, errors.WithStack(err)
@@ -66,7 +83,21 @@ func handleLeaveWorkgroup(ctx context.Context, rawWorkgroupID string) (*model.Wo
 
 	repo := model.NewWorkgroupRepository(db)
 
-	workgroup, err := repo.RemoveUserFromWorkgroup(ctx, user.ID, workgroupID)
+	workgroup, err := repo.Find(ctx, workgroupID)
+	if err != nil {
+		return nil, errors.WithStack(err)
+	}
+
+	authorized, err := isAuthorized(ctx, workgroup, model.ActionLeave)
+	if err != nil {
+		return nil, errs.WithStack(err)
+	}
+
+	if !authorized {
+		return nil, errs.WithStack(ErrForbidden)
+	}
+
+	workgroup, err = repo.RemoveUserFromWorkgroup(ctx, user.ID, workgroup.ID)
 	if err != nil {
 		return nil, errors.WithStack(err)
 	}
@@ -75,6 +106,15 @@ func handleLeaveWorkgroup(ctx context.Context, rawWorkgroupID string) (*model.Wo
 }
 
 func handleCreateWorkgroup(ctx context.Context, changes model.WorkgroupChanges) (*model.Workgroup, error) {
+	authorized, err := isAuthorized(ctx, &model.Workgroup{}, model.ActionCreate)
+	if err != nil {
+		return nil, errs.WithStack(err)
+	}
+
+	if !authorized {
+		return nil, errs.WithStack(ErrForbidden)
+	}
+
 	db, err := getDB(ctx)
 	if err != nil {
 		return nil, errors.WithStack(err)
@@ -90,12 +130,7 @@ func handleCreateWorkgroup(ctx context.Context, changes model.WorkgroupChanges)
 	return workgroup, nil
 }
 
-func handleCloseWorkgroup(ctx context.Context, rawWorkgroupID string) (*model.Workgroup, error) {
-	workgroupID, err := parseWorkgroupID(rawWorkgroupID)
-	if err != nil {
-		return nil, errors.WithStack(err)
-	}
-
+func handleCloseWorkgroup(ctx context.Context, workgroupID string) (*model.Workgroup, error) {
 	db, err := getDB(ctx)
 	if err != nil {
 		return nil, errors.WithStack(err)
@@ -103,7 +138,21 @@ func handleCloseWorkgroup(ctx context.Context, rawWorkgroupID string) (*model.Wo
 
 	repo := model.NewWorkgroupRepository(db)
 
-	workgroup, err := repo.CloseWorkgroup(ctx, workgroupID)
+	workgroup, err := repo.Find(ctx, workgroupID)
+	if err != nil {
+		return nil, errors.WithStack(err)
+	}
+
+	authorized, err := isAuthorized(ctx, workgroup, model.ActionClose)
+	if err != nil {
+		return nil, errs.WithStack(err)
+	}
+
+	if !authorized {
+		return nil, errs.WithStack(ErrForbidden)
+	}
+
+	workgroup, err = repo.CloseWorkgroup(ctx, workgroup.ID)
 	if err != nil {
 		return nil, errors.WithStack(err)
 	}
@@ -111,12 +160,7 @@ func handleCloseWorkgroup(ctx context.Context, rawWorkgroupID string) (*model.Wo
 	return workgroup, nil
 }
 
-func handleUpdateWorkgroup(ctx context.Context, rawWorkgroupID string, changes model.WorkgroupChanges) (*model.Workgroup, error) {
-	workgroupID, err := parseWorkgroupID(rawWorkgroupID)
-	if err != nil {
-		return nil, errors.WithStack(err)
-	}
-
+func handleUpdateWorkgroup(ctx context.Context, workgroupID string, changes model.WorkgroupChanges) (*model.Workgroup, error) {
 	db, err := getDB(ctx)
 	if err != nil {
 		return nil, errors.WithStack(err)
@@ -124,19 +168,24 @@ func handleUpdateWorkgroup(ctx context.Context, rawWorkgroupID string, changes m
 
 	repo := model.NewWorkgroupRepository(db)
 
-	workgroup, err := repo.UpdateWorkgroup(ctx, workgroupID, changes)
+	workgroup, err := repo.Find(ctx, workgroupID)
+	if err != nil {
+		return nil, errors.WithStack(err)
+	}
+
+	authorized, err := isAuthorized(ctx, workgroup, model.ActionUpdate)
+	if err != nil {
+		return nil, errs.WithStack(err)
+	}
+
+	if !authorized {
+		return nil, errs.WithStack(ErrForbidden)
+	}
+
+	workgroup, err = repo.UpdateWorkgroup(ctx, workgroup.ID, changes)
 	if err != nil {
 		return nil, errors.WithStack(err)
 	}
 
 	return workgroup, nil
 }
-
-func parseWorkgroupID(workgroupID string) (uint, error) {
-	workgroupID64, err := strconv.ParseUint(workgroupID, 10, 32)
-	if err != nil {
-		return 0, errors.WithStack(err)
-	}
-
-	return uint(workgroupID64), nil
-}
diff --git a/internal/model/action.go b/internal/model/action.go
new file mode 100644
index 0000000..737096b
--- /dev/null
+++ b/internal/model/action.go
@@ -0,0 +1,13 @@
+package model
+
+type Action string
+
+const (
+	ActionCreate Action = "create"
+	ActionRead   Action = "read"
+	ActionUpdate Action = "update"
+	ActionDelete Action = "delete"
+	ActionJoin   Action = "join"
+	ActionLeave  Action = "leave"
+	ActionClose  Action = "close"
+)
diff --git a/internal/model/dsf_repository.go b/internal/model/dsf_repository.go
index bfc3be0..1292458 100644
--- a/internal/model/dsf_repository.go
+++ b/internal/model/dsf_repository.go
@@ -88,6 +88,17 @@ func (r *DSFRepository) updateFromChanges(dsf *DecisionSupportFile, changes *Dec
 	return nil
 }
 
+func (r *DSFRepository) Find(ctx context.Context, id string) (*DecisionSupportFile, error) {
+	dsf := &DecisionSupportFile{}
+	query := r.db.Model(dsf).Preload("Workgroup").Where("id = ?", id)
+
+	if err := query.First(&dsf).Error; err != nil {
+		return nil, errs.WithStack(err)
+	}
+
+	return dsf, nil
+}
+
 func (r *DSFRepository) Search(ctx context.Context, filter *DecisionSupportFileFilter) ([]*DecisionSupportFile, error) {
 	query := r.db.Model(&DecisionSupportFile{}).Preload("Workgroup")
 
diff --git a/internal/model/dsf_voter.go b/internal/model/dsf_voter.go
new file mode 100644
index 0000000..baa4c7d
--- /dev/null
+++ b/internal/model/dsf_voter.go
@@ -0,0 +1,48 @@
+package model
+
+import (
+	"context"
+
+	"forge.cadoles.com/Cadoles/daddy/internal/voter"
+)
+
+type DecisionSupportFileVoter struct {
+}
+
+func (v *DecisionSupportFileVoter) Vote(ctx context.Context, subject interface{}, obj interface{}, act interface{}) (voter.Decision, error) {
+	user, ok := subject.(*User)
+	if !ok {
+		return voter.Abstain, nil
+	}
+
+	dsf, ok := obj.(*DecisionSupportFile)
+	if !ok {
+		return voter.Abstain, nil
+	}
+
+	action, ok := act.(Action)
+	if !ok {
+		return voter.Abstain, nil
+	}
+
+	switch action {
+	case ActionCreate:
+		return voter.Allow, nil
+	case ActionRead:
+		return voter.Allow, nil
+	case ActionUpdate:
+		if inWorkgroup(user, dsf.Workgroup) {
+			return voter.Allow, nil
+		}
+
+		return voter.Deny, nil
+	case ActionDelete:
+		return voter.Deny, nil
+	}
+
+	return voter.Abstain, nil
+}
+
+func NewDecisionSupportFileVoter() *DecisionSupportFileVoter {
+	return &DecisionSupportFileVoter{}
+}
diff --git a/internal/model/helper.go b/internal/model/helper.go
new file mode 100644
index 0000000..9f56dd9
--- /dev/null
+++ b/internal/model/helper.go
@@ -0,0 +1,15 @@
+package model
+
+func inWorkgroup(user *User, workgroup *Workgroup) bool {
+	if workgroup == nil {
+		return false
+	}
+
+	for _, w := range user.Workgroups {
+		if w.ID == workgroup.ID {
+			return true
+		}
+	}
+
+	return false
+}
diff --git a/internal/model/user_repository.go b/internal/model/user_repository.go
index f84a70c..378982b 100644
--- a/internal/model/user_repository.go
+++ b/internal/model/user_repository.go
@@ -7,6 +7,7 @@ import (
 	"forge.cadoles.com/Cadoles/daddy/internal/orm"
 	"github.com/jinzhu/gorm"
 	"github.com/pkg/errors"
+	errs "github.com/pkg/errors"
 )
 
 type UserRepository struct {
@@ -68,6 +69,17 @@ func (r *UserRepository) UpdateUserByEmail(ctx context.Context, email string, ch
 	return user, nil
 }
 
+func (r *UserRepository) Find(ctx context.Context, id string) (*User, error) {
+	user := &User{}
+	query := r.db.Model(user).Where("id = ?", id)
+
+	if err := query.First(&user).Error; err != nil {
+		return nil, errs.WithStack(err)
+	}
+
+	return user, nil
+}
+
 func NewUserRepository(db *gorm.DB) *UserRepository {
 	return &UserRepository{db}
 }
diff --git a/internal/model/workgroup_repository.go b/internal/model/workgroup_repository.go
index 283c1fe..6f83de0 100644
--- a/internal/model/workgroup_repository.go
+++ b/internal/model/workgroup_repository.go
@@ -6,6 +6,7 @@ import (
 
 	"github.com/jinzhu/gorm"
 	"github.com/pkg/errors"
+	errs "github.com/pkg/errors"
 )
 
 type WorkgroupRepository struct {
@@ -47,7 +48,7 @@ func (r *WorkgroupRepository) CreateWorkgroup(ctx context.Context, changes Workg
 		Name: changes.Name,
 	}
 
-	if err := r.db.Model(&Workgroup{}).Create(workgroup).Error; err != nil {
+	if err := r.db.Model(&Workgroup{}).Preload("Members").Create(workgroup).Error; err != nil {
 		return nil, errors.WithStack(err)
 	}
 
@@ -135,6 +136,17 @@ func (r *WorkgroupRepository) RemoveUserFromWorkgroup(ctx context.Context, userI
 	return workgroup, nil
 }
 
+func (r *WorkgroupRepository) Find(ctx context.Context, id string) (*Workgroup, error) {
+	wg := &Workgroup{}
+	query := r.db.Model(wg).Preload("Members").Where("id = ?", id)
+
+	if err := query.First(&wg).Error; err != nil {
+		return nil, errs.WithStack(err)
+	}
+
+	return wg, nil
+}
+
 func NewWorkgroupRepository(db *gorm.DB) *WorkgroupRepository {
 	return &WorkgroupRepository{db}
 }
diff --git a/internal/model/workgroup_voter.go b/internal/model/workgroup_voter.go
new file mode 100644
index 0000000..d9e8fc0
--- /dev/null
+++ b/internal/model/workgroup_voter.go
@@ -0,0 +1,54 @@
+package model
+
+import (
+	"context"
+
+	"forge.cadoles.com/Cadoles/daddy/internal/voter"
+)
+
+type WorkgroupVoter struct {
+}
+
+func (v *WorkgroupVoter) Vote(ctx context.Context, subject interface{}, obj interface{}, act interface{}) (voter.Decision, error) {
+	user, ok := subject.(*User)
+	if !ok {
+		return voter.Abstain, nil
+	}
+
+	workgroup, ok := obj.(*Workgroup)
+	if !ok {
+		return voter.Abstain, nil
+	}
+
+	action, ok := act.(Action)
+	if !ok {
+		return voter.Abstain, nil
+	}
+
+	switch action {
+	case ActionCreate:
+		return voter.Allow, nil
+	case ActionRead:
+		return voter.Allow, nil
+	case ActionJoin:
+		return voter.Allow, nil
+	case ActionLeave:
+		fallthrough
+	case ActionUpdate:
+		fallthrough
+	case ActionClose:
+		if inWorkgroup(user, workgroup) {
+			return voter.Allow, nil
+		} else {
+			return voter.Deny, nil
+		}
+	case ActionDelete:
+		return voter.Deny, nil
+	}
+
+	return voter.Abstain, nil
+}
+
+func NewWorkgroupVoter() *WorkgroupVoter {
+	return &WorkgroupVoter{}
+}
diff --git a/internal/route/mount.go b/internal/route/mount.go
index aa8109a..b295101 100644
--- a/internal/route/mount.go
+++ b/internal/route/mount.go
@@ -36,10 +36,12 @@ func Mount(r *chi.Mux, config *config.Config) error {
 		}).Handler)
 		r.Use(session.UserEmailMiddleware)
 
+		gqlConfig := generated.Config{
+			Resolvers: &graph.Resolver{},
+		}
+
 		gql := handler.New(
-			generated.NewExecutableSchema(generated.Config{
-				Resolvers: &graph.Resolver{},
-			}),
+			generated.NewExecutableSchema(gqlConfig),
 		)
 
 		gql.AddTransport(transport.POST{})
diff --git a/internal/voter/decision.go b/internal/voter/decision.go
new file mode 100644
index 0000000..bbf299e
--- /dev/null
+++ b/internal/voter/decision.go
@@ -0,0 +1,22 @@
+package voter
+
+type Decision int
+
+const (
+	Allow Decision = iota
+	Deny
+	Abstain
+)
+
+func AsString(d Decision) string {
+	switch d {
+	case Allow:
+		return "allow"
+	case Deny:
+		return "deny"
+	case Abstain:
+		return "abstain"
+	default:
+		return "unknown"
+	}
+}
diff --git a/internal/voter/manager.go b/internal/voter/manager.go
new file mode 100644
index 0000000..cf56bd7
--- /dev/null
+++ b/internal/voter/manager.go
@@ -0,0 +1,60 @@
+package voter
+
+import (
+	"context"
+
+	"github.com/pkg/errors"
+	"gitlab.com/wpetit/goweb/logger"
+)
+
+type Voter interface {
+	Vote(ctx context.Context, subject interface{}, obj interface{}, action interface{}) (Decision, error)
+}
+
+type Strategy func(ctx context.Context, decisions []Decision) (Decision, error)
+
+type Manager struct {
+	strategy Strategy
+	voters   []Voter
+}
+
+func (m *Manager) Authorized(ctx context.Context, subject interface{}, obj interface{}, action interface{}) (Decision, error) {
+	decisions := make([]Decision, 0, len(m.voters))
+
+	logger.Debug(
+		ctx,
+		"checking authorization",
+		logger.F("subject", subject),
+		logger.F("object", obj),
+		logger.F("action", action),
+	)
+
+	for _, v := range m.voters {
+		dec, err := v.Vote(ctx, subject, obj, action)
+		if err != nil {
+			return Deny, errors.WithStack(err)
+		}
+
+		decisions = append(decisions, dec)
+	}
+
+	result, err := m.strategy(ctx, decisions)
+	if err != nil {
+		return Deny, errors.WithStack(err)
+	}
+
+	logger.Debug(
+		ctx,
+		"authorization checked",
+		logger.F("subject", subject),
+		logger.F("object", obj),
+		logger.F("action", action),
+		logger.F("result", AsString(result)),
+	)
+
+	return result, nil
+}
+
+func NewManager(strategy Strategy, voters ...Voter) *Manager {
+	return &Manager{strategy, voters}
+}
diff --git a/internal/voter/provider.go b/internal/voter/provider.go
new file mode 100644
index 0000000..e20f68e
--- /dev/null
+++ b/internal/voter/provider.go
@@ -0,0 +1,13 @@
+package voter
+
+import (
+	"gitlab.com/wpetit/goweb/service"
+)
+
+func ServiceProvider(strategy Strategy, voters ...Voter) service.Provider {
+	manager := NewManager(strategy, voters...)
+
+	return func(ctn *service.Container) (interface{}, error) {
+		return manager, nil
+	}
+}
diff --git a/internal/voter/service.go b/internal/voter/service.go
new file mode 100644
index 0000000..9f1d355
--- /dev/null
+++ b/internal/voter/service.go
@@ -0,0 +1,33 @@
+package voter
+
+import (
+	"github.com/pkg/errors"
+	"gitlab.com/wpetit/goweb/service"
+)
+
+const ServiceName service.Name = "voter"
+
+// From retrieves the voter service in the given container.
+func From(container *service.Container) (*Manager, error) {
+	service, err := container.Service(ServiceName)
+	if err != nil {
+		return nil, errors.Wrapf(err, "error while retrieving '%s' service", ServiceName)
+	}
+
+	srv, ok := service.(*Manager)
+	if !ok {
+		return nil, errors.Errorf("retrieved service is not a valid '%s' service", ServiceName)
+	}
+
+	return srv, nil
+}
+
+// Must retrieves the voter service in the given container or panic otherwise.
+func Must(container *service.Container) *Manager {
+	srv, err := From(container)
+	if err != nil {
+		panic(err)
+	}
+
+	return srv
+}
diff --git a/internal/voter/strategy.go b/internal/voter/strategy.go
new file mode 100644
index 0000000..34d9668
--- /dev/null
+++ b/internal/voter/strategy.go
@@ -0,0 +1,77 @@
+package voter
+
+import "context"
+
+// StrategyUnanimous returns Allow if all voters allow the operations.
+func StrategyUnanimous(ctx context.Context, decisions []Decision) (Decision, error) {
+	allAbstains := true
+
+	for _, d := range decisions {
+		if d == Deny {
+			return Deny, nil
+		}
+
+		if d != Abstain {
+			allAbstains = false
+		}
+	}
+
+	if allAbstains {
+		return Abstain, nil
+	}
+
+	return Allow, nil
+}
+
+// StrategyAffirmative returns Allow if at least one voter allow the operation.
+func StrategyAffirmative(ctx context.Context, decisions []Decision) (Decision, error) {
+	allAbstains := true
+
+	for _, d := range decisions {
+		if d == Allow {
+			return Allow, nil
+		}
+
+		if allAbstains && d != Abstain {
+			allAbstains = false
+		}
+	}
+
+	if allAbstains {
+		return Abstain, nil
+	}
+
+	return Deny, nil
+}
+
+// StrategyConsensus returns Allow if the majority of voters allow the operation.
+func StrategyConsensus(ctx context.Context, decisions []Decision) (Decision, error) {
+	deny := 0
+	allow := 0
+	abstain := 0
+
+	for _, d := range decisions {
+		switch {
+		case d == Allow:
+			allow++
+		case d == Deny:
+			deny++
+		case d == Abstain:
+			abstain++
+		}
+	}
+
+	if abstain > allow && abstain > deny {
+		return Abstain, nil
+	}
+
+	if allow > abstain && allow > deny {
+		return Allow, nil
+	}
+
+	if deny > allow && deny > abstain {
+		return Deny, nil
+	}
+
+	return Abstain, nil
+}
diff --git a/internal/voter/strategy_test.go b/internal/voter/strategy_test.go
new file mode 100644
index 0000000..f01de52
--- /dev/null
+++ b/internal/voter/strategy_test.go
@@ -0,0 +1,125 @@
+package voter
+
+import (
+	"context"
+	"testing"
+)
+
+func TestStrategyUnanimous(t *testing.T) {
+	testCases := []struct {
+		Decisions []Decision
+		Expect    Decision
+	}{
+		{
+			Decisions: []Decision{Allow, Allow, Allow},
+			Expect:    Allow,
+		},
+		{
+			Decisions: []Decision{Abstain, Abstain, Abstain},
+			Expect:    Abstain,
+		},
+		{
+			Decisions: []Decision{Deny, Abstain, Abstain},
+			Expect:    Deny,
+		},
+		{
+			Decisions: []Decision{Deny, Allow, Abstain},
+			Expect:    Deny,
+		},
+	}
+
+	for _, tc := range testCases {
+		ctx := context.Background()
+
+		result, err := StrategyUnanimous(ctx, tc.Decisions)
+		if err != nil {
+			t.Error(err)
+		}
+
+		if e, g := tc.Expect, result; e != g {
+			t.Errorf("result: expected '%v', got '%v'", AsString(e), AsString(g))
+		}
+	}
+}
+
+func TestStrategyAffirmative(t *testing.T) {
+	testCases := []struct {
+		Decisions []Decision
+		Expect    Decision
+	}{
+		{
+			Decisions: []Decision{Allow, Allow, Allow},
+			Expect:    Allow,
+		},
+		{
+			Decisions: []Decision{Abstain, Abstain, Abstain},
+			Expect:    Abstain,
+		},
+		{
+			Decisions: []Decision{Deny, Abstain, Abstain},
+			Expect:    Deny,
+		},
+		{
+			Decisions: []Decision{Deny, Allow, Abstain},
+			Expect:    Allow,
+		},
+	}
+
+	for _, tc := range testCases {
+		ctx := context.Background()
+
+		result, err := StrategyAffirmative(ctx, tc.Decisions)
+		if err != nil {
+			t.Error(err)
+		}
+
+		if e, g := tc.Expect, result; e != g {
+			t.Errorf("result: expected '%v', got '%v'", AsString(e), AsString(g))
+		}
+	}
+}
+
+func TestStrategyConsensus(t *testing.T) {
+	testCases := []struct {
+		Decisions []Decision
+		Expect    Decision
+	}{
+		{
+			Decisions: []Decision{Allow, Allow, Allow},
+			Expect:    Allow,
+		},
+		{
+			Decisions: []Decision{Abstain, Abstain, Abstain},
+			Expect:    Abstain,
+		},
+		{
+			Decisions: []Decision{Deny, Allow, Abstain},
+			Expect:    Abstain,
+		},
+		{
+			Decisions: []Decision{Deny, Deny, Allow},
+			Expect:    Deny,
+		},
+		{
+			Decisions: []Decision{Deny, Deny, Allow, Allow},
+			Expect:    Abstain,
+		},
+		{
+			Decisions: []Decision{Deny, Deny, Allow, Allow, Allow},
+			Expect:    Allow,
+		},
+	}
+
+	for _, tc := range testCases {
+		ctx := context.Background()
+
+		result, err := StrategyConsensus(ctx, tc.Decisions)
+		if err != nil {
+			t.Error(err)
+		}
+
+		if e, g := tc.Expect, result; e != g {
+			t.Errorf("result: expected '%v', got '%v'", AsString(e), AsString(g))
+		}
+	}
+}